What Utilities Must Consider in Tender Specifications for SF₆-Free GIS

A practical guide to writing clear, future-proof procurement requirements for modern, climate-friendly MV switchgear.

Utilities across Europe, the Middle East, Asia, and the Americas are increasingly transitioning away from sulphur hexafluoride (SF₆) in medium-voltage switchgear. Regulations such as the EU F-Gas Regulation (2024/573), national decarbonization targets, and corporate net-zero strategies are accelerating the shift. As SF₆ alternatives such as dry-air GIS mature, utilities must update their tender documentation to ensure safe, reliable, and compliant technology is procured.

This article provides a structured overview of what utilities should consider when specifying SF₆-free GIS, helping buyers avoid ambiguity, minimize risk, and ensure long-term grid compatibility.

1. Regulatory and Environmental Requirements

1.1 Compliance with EU F-Gas Regulation (2024/573)

Tenders should explicitly require compliance with the latest restrictions on SF₆ use in MV equipment, including timelines and exemptions.

Recommended specification language:

“The offered switchgear must be SF₆-free and comply fully with EU Regulation (EU) 2024/573, including all prohibitions on SF₆ in new MV equipment.”

1.2 Global Warming Potential (GWP) criteria

Ensure gas mixtures used in GIS have GWP = 0 (dry air, clean air).

Avoid fluorinated gas blends with non-zero GWP.

1.3 Lifecycle environmental impact

Utilities increasingly require:

• ISO 14040/44 LCA documentation
• End-of-life handling procedures
• Avoidance of hazardous arc by-products

Dry-air GIS is advantageous, as PD and arc decomposition generate no toxic fluorinated compounds.

2. Technical Performance Requirements

At minimum, tenders should require the same performance levels expected from SF₆ GIS. Modern SF₆-free GIS can meet — and often exceed —these levels.

2.1 Rated voltage and insulation coordination

Specify:

• U_r (e.g., 24 kV / 36 kV)
• Lightning impulse withstand voltage values (e.g., 125 kV / 170 kV)
• Power frequency withstand voltage values

Tender tip:

Require IEC 62271-1 and IEC 62271-200 compliance for insulation performance.

2.2 Short-circuit ratings

Specify:

• Rated short-time withstand current: 16 / 25 / 31.5 kA
• Duration: 1 or 3 s
• Peak withstand current (depending on frequency)

2.3 Internal Arc Classification (IAC)

Define:

• Accessibility: A (for authorized personnel only)
• Sides: FL or FLR
• Current: 16 / 25 / 31.5 kA
• Time: 1 s

Example requirement:

“IAC AFLR 25 kA / 1s for all functional units, tested per IEC 62271-200.”

2.4 Partial discharge performance

Specify:

• PD < 5 pC at rated voltage
• Routine-test certificates for each panel

Dry-air GIS typically offers very high PD inception due to robust solid insulation.

2.5 Switching technology

Most modern SF₆-free GIS use:

• Vacuum interrupters for breaking
• Dry air for insulation

Tender documents should require:

• VCB technology per IEC 62271-100
• Capacitive and inductive switching performance
• Auto-reclose capability (if needed)

3. Construction, Safety & Compartmentalization

3.1 Compartment separation

Require:

• Metal-enclosed, compartmentalized design
• Dedicated compartments for busbar, breaker, and cables
• Mechanical segregation for safe maintenance

3.2 Pressure behaviour and gas handling

Specify:

• No gas handling equipment required during installation

This reduces OPEX, complexity, and safety risks.

3.3 Arc by-product safety

Explicitly address gas toxicity concerns:

“Switchgear must not generate toxic or corrosive gas by-products during internal arc or partial discharge events.”

This excludes SF₆ and F-gas mixtures that decompose into HF, SOF₂, SO₂F₂, etc.

4. Digitalization & Monitoring Requirements

Utilities increasingly expect GIS to be “digital-ready.”

Tender specs should include:

4.1 Sensor readiness

• Temperature monitoring (busbar, cable connections)
• Partial discharge sensors (UHF / TEV / HFCT)
• Gas-density monitoring

4.2 SCADA integration

Specify supported protocols:

• IEC 61850
• IEC 60870-5-101/104
• Modbus or DNP3

4.3 Cybersecurity

Ask for:

• Secure firmware
• Encrypted communication
• Role-based access control

5. Installation & Operational Requirements

5.1 Dimensions and footprint

Ask vendors to provide:

• Panel widths
• Cable termination space
• Front access vs rear access needs

GIS for renewables and data centres often prioritizes compactness.

5.2 Cable termination compatibility

Specify:

• T-connectors (630 A / 1250 A) for C-type bushings
• Cable insulation types (XLPE, EPR)
• Cable sizes for industrial feeders

5.3 Maintenance & lifecycle

Require:

• Maintenance-free or low-maintenance design
• Normally no gas refilling over lifetime needed
• 30-year design life (minimum)

Dry-air GIS is typically sealed for life.

6. Documentation and Certification Requirements

Tenders should require:

• Complete type-test reports (IEC 62271-200 / 100 / 102 / 103)
• Routine-test reports for each panel
• Factory acceptance test (FAT) documentation
• Installation and operation manuals
• LCA reports (where applicable)
• Environmental compliance declarations

To ensure quality, many utilities require that type-tests are from:

• Accredited independent laboratories (e.g., STL members)
• Third-party witnessed tests

7. Avoiding Ambiguity: Recommended Specification Language

Many tenders fail due to unclear or outdated wording.

Here is a recommended structure:

“The switchgear must be SF₆-free and use a gas mixture with GWP = 0. Only dry-air or clean-air insulated GIS designs are acceptable. The equipment must comply with IEC 62271-200, offer IAC AFLR 25 kA / 1s, and utilize vacuum interrupters per IEC 62271-100. No fluorinated gases, gas handling equipment, are permitted.”

This wording avoids confusion with F-gas blends (G³, AirPlus, fluoronitriles, etc.).

8. Conclusion

Specifying SF₆-free GIS requires utilities to consider technical performance, environmental compliance, safety, digitalization, and lifecycle impacts. By clearly defining requirements for insulation, arc safety, compartmentalization, PD performance, and monitoring, utilities can ensure procured equipment is:

• Safe
• Reliable
• Environmentally compliant
• Future-proof
• Cost-effective over its lifetime

SF₆-free GIS has matured, and tender documents should reflect the technology’s capabilities rather than legacy SF₆ constraints. When written correctly, tender specifications can accelerate the transition to modern, sustainable grid infrastructure.